Trenchers or diggers are known. These trenchers are of the variety wherein they may be ridden by the operator or, alternatively, they may be controlled by an operator from a position not on the trencher as, for example, walking adjacent thereto. All of such known trenchers suffer from various disadvantages which are inherent in the several designs.
In one known trencher, for example, the digger apparatus is located in a position some distance behind the rearward wheels. There is significant force generated on the chain by the digger tools during the operation of the digger. Such force creates a moment on the trencher frame which tends to raise the forward wheels of the trencher off the ground. Such force on the digger tools also produces impact loading which tends to make the machine buck or jerk while under operation. To reduce these problems, weight has been added to the frame which weight, however, can cause the trencher to be unnecessarily heavy. In any event, such added weight is inefficient.
A further problem with known trenchers involves the steering control system. Some known trenchers use a skid type steering system which, because of its jerkiness, can cause difficulties in cutting smooth curves which may be highly desirable for certain applications. Other trenchers use steerable front wheels but such trenchers are usually ridden by an operator where the steering wheel is not left unattended and, therefore, such previous trencher steering systems used in "operator ridden" applications are not self-locking which is desirable in non-riding applications where the steering function may well be left unattended for a certain time.
Yet a further problem in existing trenchers relates to the power or drive wheels. Where the power or drive wheels are not in a position nearest to the digger chain, the drive wheels are not obtaining the maximum downward force benefit from the chain and, therefore, the drive wheels are acting in a less efficient manner.
Yet a further problem relates to the digger or cutting chain. It is desirable, for efficient cutting, that the speed of the cutting chain be maintained at its most desirable revolution rate. When digging through hard dirt or in rocks, for example, the engine speed may well decrease. It is desirable, therefore, to reduce the pressure of the digger chain on the soil so as to bring the engine speed back to its normal rate. Such manual manipulation of the controls, however, is tedious and requires constant monitoring by the operator.
Yet a further problem relates to the inherent tendency of a trencher to be moved by the cutting action of the digger chain when the cutting action into the ground is commenced. The digging action under certain digging conditions can lift the rearward driving wheels off the ground which thereby allows the trencher to be propelled rearwardly creating an unexpected and potentially unsafe situation.